1. Field of the Invention
The present invention relates to a display device having a backlight and an optical device applicable to the same and other devices.
2. Description of the Related Art
Display devices are known which have a backlight using two or more light sources in combination. For example, Japanese Patent Laid-Open No. 2005-275644 relates to a touch panel liquid crystal display device. In this display device, the backlight radiates visible and invisible light onto the display panel. The image is displayed with the visible light. The detection target (e.g., user's finger) in proximity to the display panel is detected by detecting, with sensors, the invisible light reflected by the detection target. This document discloses the backlight configuration using two types of light sources in combination, i.e., visible and invisible light sources.